Key Reactions Employing Perovskite Catalysis
Introduction
With their unique crystal structures and remarkable catalytic properties, perovskite materials have become the focus of much attention within the arena of catalysis.
The catalytic performances could be optimized by adjustment of the A-site and B-site metal ions and even the lattice structure of perovskite catalysts. For example, perovskite oxides, including LaFeO₃ and SrCoO₃, are widely applied in oxygen reduction reactions, while perovskite nitrides, represented by LaNiO₃, have shown high efficiency in nitrogenation reactions. With high surface areas and excellent electrical conductivity, perovskites are also ideal catalytic supports in energy conversion and pollutant degradation.
1. Oxygen Evolution Reaction (OER)
The oxygen evolution reaction is a crucial reaction in water electrolysis used for hydrogen production; it finds broad applications in renewable energy generation. Perovskite materials, indeed, have represented an outstanding catalytic activity toward this reaction, especially concerning stability and durability. In particular, perovskite oxides such as LaCoO₃ and BaSrCo₃ continue to be active at high temperatures and under acidic conditions, making them ideal candidates for OER applications.
Case Study: LaCoO₃ catalysts have been reported to be superior to conventional catalysts such as RuO₂ in acidic media in terms of cost-effectiveness and stability in the long run. This makes LaCoO₃ more catalytically active, due to the oxygen desorption that is accelerated by generating surface oxygen vacancies.
The catalytic performance of perovskite catalysts in OER is not only affected by the materials themselves, but also by factors such as lattice defects, oxygen vacancies, and metal ion migration. The synthesis methods and structures of perovskite materials can be optimized to further enhance their catalytic performance in OER.
2. Carbon Dioxide Reduction Reaction (CO₂RR)
The carbon dioxide reduction reaction is considered one of the promising catalytic processes, in which the greenhouse gas CO₂ will be converted into value-added chemicals or fuels. In this regard, perovskite materials are playing an important role in CO₂RR, especially in improving reaction selectivity and the distribution of products. LaNiO₃ and SrTiO₃ exhibit excellent activity for CO₂ reduction due to their unique electronic structure and good electron conductivity.
Case Study: LaNiO₃ catalysts have demonstrated unparalleled efficiency in CO₂RR for the production of carbon monoxide and methanol with better selectivity and longer catalytic lifetime compared to conventional catalysts. LaNiO₃ improves CO₂ adsorption on the catalytic surface by optimizing metal ion coordination, which enhances the efficiency of CO₂ conversion.
The Perovskite catalyst for CO₂RR not only supplies the active sites but also facilitates electron and proton transfer in the reaction processes, which indeed make them ideal candidates toward CO₂ reduction. This is because of their ability to tune their electronic properties for better adsorption and conversion of CO₂.
3. Hydrogen Production (Hydrogen Evolution Reaction, HER)
Hydrogen is a clean energy source that would play a vital role in future energy systems. The hydrogen evolution reaction is the main process related to hydrogen production via water electrolysis. Perovskite materials have shown excellent catalytic performance in HER; some oxides, like LaNiO₃, LaFeO₃, and BaFeO₃, are widely used.
Case Study: Investigations have shown that LaNiO₃ catalysts represent an outstanding performance in hydrogen generation with high catalytic activity and low overpotential. Its hydrogen production rate surpasses many conventional platinum-based catalysts. In alkaline environments, LaNiO₃ significantly lowers the overpotential of the reaction, hence giving rise to a higher electrochemical activity.
Through tuning the structure of perovskite materials by doping with rare-earth elements or using nanostructuring, considerable enhancements in their catalytic activity regarding HER have been possible. These modifications have been responsible for increased reaction rates and overall efficiencies in hydrogen production.
4. Applications in Organic Reactions
Applications of perovskite catalysts are not limited to energy conversion reactions but also have a promising role in organic synthesis reactions. Among various organic reactions, olefin hydrogenation, aromatization, and alcohol conversions have been catalyzed by perovskite materials.
Case Study: LaFeO₃ has been found to serve as an effective catalyst in the process of olefin hydrogenation; it provides high activity in the reaction of hydrogen with olefins to form saturated hydrocarbons. Perovskite catalysts, such as LaFeO₃, exhibit better selectivity with longer catalytic lifetimes than the traditional metal catalysts.
Their versatility in organic reactions is due to the easily tunable properties of perovskites, which can be optimized according to the conditions of the reaction and the desired products.
5. Degradation of Pollutants and Environmental Catalysis
Environmental catalysis is another important field where perovskite materials play a key role. Examples such as LaCoO₃ and BaSrCo₃ have been in use for the catalytic degradation of pollutants like NOx, SO₂, and the treatment of organic waste. Perovskite materials can oxidize harmful gases into less toxic substances, hence acting as useful tools in controlling pollution.
Case Study: Perovskite materials, such as LaCoO₃ and BaSrCo₃, have shown much higher conversion rates for NO in NOx catalytic reduction compared with conventional catalysts, reducing environmental pollution. During the treatment of organic wastewater, perovskite catalysts also demonstrated high efficiency in degrading harmful organic pollutants, thus leading to cleaner industrial effluents.
Conclusion
Perovskite materials have become important in many catalytic reactions. From oxygen evolution, carbon dioxide reduction, hydrogen production, and organic reactions, the performance of perovskite materials is outstanding for all of these applications.
Reference:
[1] Dandia, Anshu & Saini, Pratibha & Sharma, Ruchi & Parewa, Vijay. (2020). Visible light driven perovskite-based photocatalysts: A new candidate for green organic synthesis by photochemical protocol. Current Research in Green and Sustainable Chemistry. 3. 100031. 10.1016/j.crgsc.2020.100031.
